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991.
Physics of Atomic Nuclei - We consider that the simultaneous development of the theory of linear canonical integral transforms among two quite distinct scientific communities, provides an... 相似文献
992.
Miguel A. Harvey María E. Díaz de Vivar Ricardo Baggio Sergio Baggio 《Journal of chemical crystallography》2011,41(11):1717-1721
Abstract
The title compound is monomeric with a Zn(II) hexacoordinated center. The coordination sphere is formed by four nitrogens from two phenanthroline molecules, one oxygen from a monodentate peroxodisulfate ion, and one oxygen from a water molecule. A non-coordinated water molecule completes the formula with an important role in the stabilization of the structure through the formation of two OHW–H···Opds bridges (acting as a donor) and one OCW–H···OHW bridge where it is an acceptor group (HW: hydration water; pds: peroxodisulfato; CW: coordinated water). The compound is triclinic, space group P-1 with a = 8.763 (3) ?, b = 9.068 (3) ?, c = 17.531 (6) ?, α = 96.48 (2)°, β = 103.94 (3)°, γ = 104.57 (3)°, V = 1286.0 (7) ?3 and Z = 2. The structure was solved by direct methods with a conventional R (on F) = 0.050 for 4534 reflections with Fo > 4σ(Fo). The compound is isomorphous with the Cd analogue (in Harvey et al. Aust J Chem 54:307, 2001). An eventual dependence of conformation and coordination mode of the peroxodisulfate anion on the ancillary organic ligand taking part in the coordination compounds analyzed is discussed. 相似文献993.
The measurement of powder flowability is a major concern for most industrial processes that deal with the handling of bulk solids as raw materials,intermediates,or products.The development of devices that measure the flowability of non-aerated powders has not progressed as rapidly as might have been hoped since most research activities have been based on various types of shear testers intended to aid the design of hoppers.A new flowability indicator named as weighted cohesion (WS) is established using newly... 相似文献
994.
995.
Density functional theory (DFT) calculations of nuclear magnetic resonance (NMR) spin–spin coupling constants (SSCCs) provide an important contribution for understanding experimentally observed values. It is known that calculated SSCCs using DFT methods correlate well with those experimentally measured. Unlike most of SSCCs, in fluorine compounds, fluorine–fluorine SSCC JFF shows that the Fermi contact (FC) term is not dominant, particularly for JFF in polyfluorinated organic molecules. In order to devise a DFT approach that would correctly reproduce the variation of SSCCs within a series of fluorine compounds, we test several DFT-based approaches, using different exchange and correlation functionals. Isotropic contributions to NMR fluorine–fluorine coupling constants (FC, spin-dipolar, SD, paramagnetic spin-orbit, PSO, and diamagnetic spin-orbit, DSO) have been calculated. Results show that DFT methods give appropriate values for nJFF (n = 4 to 7), while for geminal and vicinal JFF present large deviations from experimental values. For the latter SSCCs (2JFF and 3JFF), the four contributions (FC, SD, PSO and DSO) are analysed as a function of the local and nonlocal exchange in 1,1- and 1,2-difluoroethylene. Although FC term is not dominant for these SSCCs, the variation of this contribution with exchange is remarkable. On the other hand, SD and PSO contributions can be suitably computed without and with exact exchange, respectively. 相似文献
996.
997.
Whei Oh Lin Vanderléa De Souza 《Phosphorus, sulfur, and silicon and the related elements》2013,188(1)
Abstract As part of our studies in preparation and physical properties of Potential ligands containing l-phosphoryl(P?O)-3-3-carbonyI(C?X, X?NH, O or S) group, we have investigated the intrdinta molecular hydrogen bonding of diisoproxy- phosphorylquanidine[l] as well as the tautomerism of phosphoryl benzylisothiourea. These are of interest as in interpretation of their chelation behavior as well as in development of other potential ligands for specific metal cations. 相似文献
998.
Warô Nakanishi Satoko Hayashi 《Phosphorus, sulfur, and silicon and the related elements》2013,188(6-7):1833-1837
The lone pair-lone pair repulsion plays an important role in the nonbonded P;;;P interaction in naphthalene 1,8-positions. The conformations around P and Se in 8-(PhSe)-1-(Ph 2 P=O)C 10 H 6 are determined by the attractive O;;;Se--C 3c-4e type interaction. The P;;;Se interaction in the 1,8-positions is also discussed. 相似文献
999.
Alma Viso Roberto Fernández de la Pradilla Ana García Carlos Guerrero-Strachan Marta Alonso Mariola Tortosa 《Phosphorus, sulfur, and silicon and the related elements》2013,188(5-6):1229-1234
Abstract Readily available p-tolylsulfinimines undergo highly stereoselective [3 + 2] cycloadditions with azomethine ylides generated from α -iminoesters and LDA to produce N-sulfinylimidazolidines. In the presence of Lewis acids, p-tolylsulfinimines react with glycine iminoester enolates to produce N-sulfinylimidazolidines, after cyclization of open chain intermediates. These mechanistically diverse processes take place with excellent regio-, stereo-, and facial selectivities, and the latter is opposite to most known reactions involving sulfinimines. Some of the resulting imidazolidines have been transformed into examples of a novel class of nonsymmetrical vicinal diamines using reductive and/or hydrolytic protocols. 相似文献
1000.